As the integration level increases in a semiconductor device fabrication process, the size of a minimum pattern gradually decreases. The degree the size of the minimum pattern is reduced exceeds the resolution capability limit of a current exposure apparatus. In order to form a semiconductor device having a more micro pattern, an apparatus having a short wavelength light source and a good resolution capability is used.
To implement a micro line width required due to the high integration of devices, an X-ray or an E-beam is utilized. However, the X-ray or E-beam remains technical and productivity problems in an experimental level. A Double Exposure and Etch Technology (DEET) method has currently been proposed in order to form a micro pattern.
However, if the DEET method is employed, the Critical Dimension (CD) becomes poor because of overlay accuracy between adjacent patterns. There is a difficulty in Optical Proximity Correction (OPC) control due to circuit isolation according to the DEET method.